/*
 * Copyright 2000-2015 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.intellij.util.containers;

import com.intellij.util.ArrayUtil;
import org.jetbrains.annotations.NotNull;

/*
 * @author max
 */
public class LimitedPool<T> {
    private final int maxCapacity;
    private final ObjectFactory<T> factory;
    private Object[] storage;
    private int index;

    public LimitedPool(final int maxCapacity, @NotNull ObjectFactory<T> factory) {
        this.maxCapacity = maxCapacity;
        this.factory = factory;
        storage = new Object[10];
    }

    public interface ObjectFactory<T> {
        @NotNull
        T create();

        void cleanup(@NotNull T t);
    }

    @NotNull
    public T alloc() {
        if (index == 0) return factory.create();
        int i = --index;
        //noinspection unchecked
        T result = (T) storage[i];
        storage[i] = null;
        return result;
    }

    public void recycle(@NotNull T t) {
        factory.cleanup(t);

        if (index >= maxCapacity) return;

        ensureCapacity();
        storage[index++] = t;
    }

    private void ensureCapacity() {
        if (storage.length <= index) {
            int newCapacity = Math.min(maxCapacity, storage.length * 3 / 2);
            storage = ArrayUtil.realloc(storage, newCapacity, ArrayUtil.OBJECT_ARRAY_FACTORY);
        }
    }
}
